MAGNETIC PROPERTIES OF GLASSY (Fe- Ni)86B14 ALLOYS

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MAGNETIC PROPERTIES OF GLASSY (Fe- Ni)86B14 ALLOYS

R. Hasegawa

To cite this version:

R. Hasegawa. MAGNETIC PROPERTIES OF GLASSY (Fe- Ni)86B14 ALLOYS. Journal de

Physique Colloques, 1980, 41 (C8), pp.C8-701-C8-704. �10.1051/jphyscol:19808176�. �jpa-00220278�

JOURNAL DE PHYSIQUE CoZZoque C8, suppZ6ment au n08, Tome 4 1 , aoct 1980, pagecg-701

MAGNET1 C

PROPERTI

ES OF GLASSY ( ~ e - ~ iR~~ )f,LLOYS ~ ~

R. Hasegawa

Corporate DeveZopment Center AZZied ChemicaZ Coucporat.,on, Morristown, New Jersey 07960 U.S.A.

Abstract.

-

Therm~ma~netization, crystallization behavior, mass density and magnetostriction data obtained for g3assy (Fe-Ni) 86B64 alloys suggest that the local atomic structures resemble those of the corresponding crystalline e-Ci alloys.

INTRODUCTION

1

Previous studies of magnetic properties of glassy (Fe-Ni)80B20 alloys indicate a shift of the magnetic moment versus Fe-Ni composition (Slater- Pauling-like) curve toward lower Ni content region compared with the crystalline case, implying elect- ron charge transfer from boron to the transition metal atoms. Supporting evidence for this has been

2 3

provided by MBssbauer and NMR studies of various transition metal-metalloid base glassy alloys, although its detailed nature is not clear at this moment. Efforts to clarify the effects of the metalloids on the physical properties of metallic glasses by studying simple binary alloys such as Fe-B and Co-B have opened up some new aspects. For

4

example, recent studies iade on the Fe-B system show some unexpected magnetic behaviors including

fields up to 8x10 A/m, of the alloys was 5

studied at 4.2K and between 300 and 1040K by using a vibrating sample magnetometer.. The sensitivity

-4 -1 -1 of the magnetometer is about 10 JT kg

.

^The

mass density and the magnetostriction at room temperature were measured by a conventional

5

Archimedes' method and a bridge technique respectively.

RESULTS AND DISCUSSION

Of the alloys examined containing up to x=86 in Fe86-xNixB14, those within the range 0<_x<_43 have

been found to be fully noncrystalline. These al- loys were found to have two well-defined crystal- lization temperatures, Tcl and Tc2. The values of these quantities determined by DSC with a heating rate of 2OK/min. are listed in Table I and are, as a decrease of the Curie temperature and an increase

of the magnetic moment on Fe as the boron content

is decreased. It has been speculated that these TABLE I-Crystallization and Curie Temperatures of are results of loosely packed atomic arrangements Fe86-xNixB14 Alloys

based on bcc-like structures in the alloys with X Tcl(K> T,~(K) efa(K) BfT(K) Bf;(K) low boron contents. These findings have led us to

investigate Fe-Ni base alloys containing less than 0 680 770 55650.5 1040+5 790+5 20 at.% B. We have chosen. for the present study, 8 638 745 660+5 1013+5 94035

- .

12 643 741.5 695+10 1010+5

a pseudo-binary Fe Ni B system which can be

*

86-x x 14

16 640.5 735.5 704510

synthesized in glassy states by liquid-quenching ^A 864k10

19 644 743 725+10 A

from the melt for 05x243. 860+10

EXPERIMENTAL 22 640 729 730+15 99725 847t5

The constituent elements of purity higher than 25 658 728 730L10 988+5 824+5 99.9% were melted in vacuum by induction heating. 27 647.5 721 730+5 9605Z5 770t5

29 657 711

* *

The resultant alloys were rapidly quenched from

*

32 644 725 k 916+5 772+5

the-liquids. X-ray diffraction and differential

36 649 721

* * *

scanning calorimetry (DSC) were used to determine

43

*

^{728 m 805+5 6875~5}

the composition range in which the alloys were

*Not determined.

made noncrystalline. Magnetization behavior, in

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19808176

C8-702 ^JOURNAL DE PHYSIQUE

-xpected, somewhat higher than those determined determined from the lattice constant (a=0.2868 nm).

from thermomagnetization data taken at an average Upon heating the samples beyond Tc2, the thermo- heating rate of lK/min. The ferromagnetic Curie magnetization data indicate two crystalline phases temperatures of the noncrystalline alloys, 'aa, with ferromagnetic Curie temperatures, ahd were found to be near or higher than Tcl, and when o;~, which are given in Table I. Some representa- possible, were estimated by extrapolating the mag- tive examples of the thermomagnetization data are netization data.taken below this temperature. The shown in Fig.1. Combination of the x-ray diffrac- results are listed in Table I. X-ray diffrac- tion taken on the samples heated up above T

c2 and tion taken on samples heated up to (T fTc2)/2 the data of 8i1 and 6Z2 leads to the following

cl

results. The alloys with x525 decompose above shows that the samples consist of bcc Fe-Ni and

Tc2 into tetragonal Fe B containing small amounts glassy phases for x525 and of fcc Fe-Ni, bcc Fe- 2

Ni and glassy phases for 25<x143. For example, of Ni, bcc Fe-Ni and small amounts of fcc Fe-Ni.

the alloy Fe78Ni8B14 transforms at T <T<T For example, the crystallized alloy with x=8 con- cl c2

into a composite of a glassy phase and a bcc Fe- tains (Fe-Ni) B with the lattice parameters 2

Ni phase containing about 3.5 at.% Ni which was a=0.5088 nm and c=0.4223 nm, bcc Fe-Ni with

Fig. 1. Thermomagnetization taken with a field of 720 k ~ / m for glassy Fe7*Ni8B14 and FeSgNiz7Bl4 alloys.

The arrows indicate Curie temperatures of glassy

('af)

a and crystalline (8;) phases.

180- 160- 140- 120- 100- 80

-

h

⁶⁰

a

y

40-

w

C

2 20

c

. -

0 +

ca

-N

+

160-

a

C

140-•

2 120-

100- 80 60 40 20

I I

0.

* * *

f...

* * * **

******

* *

^f

're ^{0;,= 940k}

-

0: = 660 k t

-

\

'1 _I

t

^{@C fl-}

^-

Fe78 Ni8 914

\ 1003k

I I

-

I I

* * t

I

***

I I ^{t I}

t

* * a

0 - '

* * .

* * * *

* * a *

09 = 732 k

* a * *e*

_{* ',}

e *

+

- ^{\ *}

\ \,

0i2= 770k

-

^,'1_\

+

t *

@> ^960k

-

Fe59 Ni27 B14

\,

' I *

i

-

^I I I *<"****e.. 0.

I

*.

,

. ^,

^{, ,}

.

^{, ,}

.

^{I a}

^, .

^,

^{, * *.,}

300 400 500 600 700 800 900 1000

Temperature (k)

a=0.2869 nm and fcc Fe-Ni with a=0.3590 nm. The alloys with 25<x<_43 decompose mainly into fcc Fe-Ni with the Ni content between 40 and 46 at .%

and (Fe-Ni)2B phases. Consulting with the known

6

Curie temperatures of crystalline (Fe-Ni) B and

7 c

Fe-Ni

,

we may conclude that the values of Ofl for all x of Table I are those of (Fe-Ni)2B and the values of 8i2 for x>8 correspond to those of fcc Fe-Ni alloys.

The important point to be made here is that the first crystalline phase nucleating at T is bcc

cl Fe-Ni for x525 and fcc Fe-Ni for 25<xs43. If the first crystalline phase nucleating upon crystalli- zation of glassy alloys reflects the local short range order in the noncrystalline state as specu-

4

lated previously

,

the present results imply the local atomic arrangements are bcc-like for the glassy alloys with ~ 1 2 5 , and fcc-like for 25<x<_43.

The mass density, D, as a function of the Ni content is shown in Fig.2, in which the data are compared with those of glassy (Fe-Ni) 80B20 alloys.

It appears that D for the present alloys increases with Ni content faster than that for the system with 20 at.% B up to about ~ i / ( ~ e + ~ i ) = 0.3 or x=25. Beyond this concentration, D seems to be parallel to'that for (Fe-Ni)80B20. The fast ini- tial rise of D may be evidence for a loosely packed atomic structure changing eventually into a more densely packed one. The extrapolation of the data of D for x>25 to x=O line gives DQ~7.55 g/cm which 3 is identical to the extrapolated value of D for Feg6B14 based on the density data obtained for

the Fe-B alloys containing more than 20 at.%

4

boron

.

The actual value of D for this alloy is 7.44 g/cm 3

,

being less dense by about 0.11 g/cm 3 than that predicted on the basis of the data taken for atomically dense-random-packed (Dm) alloys such as Feg0BZ0. The implied loose-random-packing (LRP) structures for the alloys with low boroa content is not incompatible with bcc-like local atomic arrangements.

The saturation magnetic moment 1-1 per transition metal atom obtained at T=4.2 K and H=8x10 A/m is 5 shown in Fig.3 as a function of Ni concentration.

Also included in the figure are the data for glassy (Fe-Ni) 80B20 and crystalline Fe-Ni alloys for com- parison. It is noticed that

us

versus Ni content curve for the present alloys resembles that of cry- stalline Fe-Ni alloys which is not the case with (Fe-Ni)80B20 alloys. The noticeable peak of ps occuring at around 29 at.% Ni may correspond to the similar peak at about 39 at.% Ni for fcc Fe-Ni.

The difference of the Ni concentration between the two cases may correspond to a charge transfer of about 0.7 electrons per boron atom from the metal- loid to the transition metals. The smaller amount of the charge transfer compared with that (1.6 e-/

B atom) for the (Fe-Ni)80B20 case is consistent with the LRP structure mentioned above.

The linear saturation magnetostriction at room temperature, A

,

versus Ni content for the present glassy alloys is compared in Fig.4 with those for

3

Nl/(Fe

+

^NI)

Fig. 3. Saturation magnetic moment per transition Fig. 2. Mass density as a function of Ni content metal atom at 4.2 K versus Ni content for glassy for glassy (Fe-Ni)86Ba4 and (Fe-Ni)80B20 alloys. and crystalline alloys.

JOURNAL DE PHYSIQUE

C8-7%

Fig. 4 . Room temperature saturation magnetostriction as a function of Ni content for glassy and

40 -

^{I r I a 1 I I I}

- -

(D I--- ^\ \

0 \

F

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^\

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.- U L C

V)

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crystalline alloys.

7 8

polycrystalline Fe-Ni and glassy (Fe-Ni)80B20

.

z

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.-

0

- ^{I ,}

W

C

-10

ACKNOWLEDGEMENTS

For the latter alloys, the quantity As varies as The author is grateful to Elisabeth Musso who

\ ^\

I \

I

-1

^I I I I I I

-.--A

^{I t t A}

/ 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 \ 0.9 1 .O

Ni/(Fe + Ni) \\

---- ^\

- Fe-Ni (Crystalline) \ _\ -

a 2 where u is the room temperature saturation has helped him collect the data contained in

s s 8

magnetization

.

We find that this simple relation- this article. The glassy samples were made by

(Fe4Ni)86

^41' -0-

(Fe-Ni),, B,

ship does not hold for the glassy alloys contain- ing 14 at.% B. Although not precisely, A versus Ni content for the present alloys exhibits some features of the magnetostriction behavior of cry- stalline Fe-Ni alloys, implying gradual change of the local short range order from 12-fold coordina- ted DRF' to bcc-like LRP structures as the Ni con-

(Noncrystalline) \

\

tent is reduced.

CONCLUSION

Based on the thermomagnetization, crystalliza- tion behavior, mass density and magnetostriction data obtained for glassy (Fe-Ni)86B14 alloys, one may conclude that the local atomic arrangements of transition metal base noncrystalline alloys with low boron content resemble those of corresponding crystalline metallic systems without metalloids.

Thus bcc-like short range order could be realized in such glassy alloys.

Robert Costa and James Briggs, Jr.

REFERENCES

1. R. C. O'Handley, R. Hasegawa, R. Ray and C.-P.

Chou, Appl. Phys. Lett.

29,

330 (1976).

2. R. Hasegawa and C.-L Chien, Solid State Commun.

18,

-

913 (1976).

3. R. Hasegawa, W. A. Hines, L. T. Kabacoff and P. Duwez, Solid State Commun. 20, 1035 (1976);

W. A. Hines, L. T. Kabacoff, R. Hasegawa and P. Duwez, J. Appl. Phys. 49, 1724 (1978) 4. R. Hasegawa and R. Ray, J. Appl. Phys. 49,

4174 (1978).

5. M. Sullivan, Rev. Sci. Instr. 51, 382 (1980).

6. M. C. Cadeville and E. Daniel, J. Physique 449 (1966).

7. R. M. Bozorth, Femwma.gneLL6m (van Nostrand Co., Princeton, 1968) p.30 and 111.

8. R. C. O'Handley, Amohphol~rl M a g n u m

I1

(Plenum Press, New York, 1977) edited by R. A. Levy and R. Hasegawa, p.379.